Devices and methods for hip replacement

ABSTRACT

Devices and methods for use in hip replacement surgery can incorporate computer models of a patient&#39;s acetabulum and surrounding bone structure, a first patient-specific jig designed from the computer model and configured to correspond to a final installation position and orientation of a prosthetic hip implant, a second patient-specific jig, also designed from the computer model, configured to refine the procedure, if necessary, following use of the first patient-specific jig, and/or a third patient specific jig, designed from the computer model, configured to refine the procedure, if necessary, following use of the first and second patient-specific jigs, allowing the surgeon to properly position and orient the hip prosthesis. Also shown and described are novel devices for implanting an acetabular cup.

BACKGROUND

1. Technical Field

The present disclosure relates to devices and methods for thereplacement of joints, and more particularly, to patient-specific hipreplacement devices, including methods of manufacturing and using suchdevices for achieving accurate hip replacement based on computergenerated imaging of a patient.

2. Background of the Invention

One known method of treating hip and other joints with arthritis andother medical conditions is to replace surfaces of articulating jointswith prosthetic devices through surgical procedures. It is critical thatsuch prosthetic devices are accurately designed and manufactured, andare installed correctly in order to relieve pain and provide aneffective treatment method for such ailments. An orthopedic surgeonperforming such joint replacement on a patient seeks to ensure, throughsurgery, adequate placement of the prosthetic and proper reconstructionof the joint being replaced. Prosthetic components used to replace ajoint may be placed optimally by templates and jigs according to theunique anatomy of a patient before surgery occurs. A particularpatient's bone structure symmetry is one important consideration that asurgeon must consider when performing joint replacement surgery.Additionally, malposition of joint replacement prosthetics can result inpremature wear of the bearing surfaces, which may require additionalsurgeries to correct.

In the case of a hip, the condition of the patient's joint may require apartial or total replacement. A partial hip replacement involvesreplacing the femoral head (the ball) of the damaged hip joint; however,the acetabulum (the socket) is not replaced in a partial hip replacementsurgery. A total hip replacement includes replacing both the femoralhead and the acetabulum with prosthetic devices. The femoral head isreplaced with a femoral prosthetic that typically includes a headportion and a stem. The stem extends into the femur of the patient andis utilized to secure the femoral device to the femur, with the headportion protruding out from the femur. The acetabulum is then resurfacedand replaced with a cup-shaped acetabular device. The cup-shapedacetabular device provides a bearing surface for the head portion of thefemoral prosthetic to allow a desirable amount of range of motion viathe joint upon total hip replacement.

To replace the acetabulum effectively, a surgeon will typically enlargethe acetabulum with a reamer machine and reamer head to create aresurfaced cavity to receive a prosthetic acetabular cup, which may ormay not be secured by cement or bone screws. One particular issue ofconcern during the reaming portion of the surgery is that the cuttingportion of the reamer is hemispherical while the prosthetic acetabularcup is typically sub-hemispherical. If the acetabulum is reamed toodeeply, the prosthetic acetabular cup will be positioned too deep withinthe reamed cavity. If the acetabulum is reamed too shallowly, theprosthetic acetabular cup will not be positioned deep enough. If theacetabulum is reamed at an improper angle, the prosthetic acetabular cupwill not be installed properly. These imperfections can causemalalignment of the prosthetic hip joint. Moreover even if theacetabular bone is properly reamed, it is quite difficult with standardtechniques to place the acetabular prosthetic cup. Recent studies,reflect a 50% rate of error in placement of the acetabular cup from anacceptably optimal range of positions when standard techniques areutilized. Thus, accurate reaming of the acetabulum and accuratepositioning of the prosthetic acetabular cup are critical.

With the assistance of computer generated data derived from CT, MRI, orother scans, such as X-rays, surgeons can more effectively determineproper alignment and positioning of the prosthetic acetabular cup in apatient through 3D modeling and rendering. While some surgeons uselasers or peripheral guide pins during surgery in an attempt to properlyplace the prosthetic acetabular cup; however, accuracy and simplicity ofexisting devices and methods remain limited due to a variety of factors.

BRIEF SUMMARY

The present disclosure pertains to patient-specific hip replacementdevices and methods of designing and manufacturing such devices forachieving accurate acetabular component placement during hip replacementsurgery based on computer generated imaging of a particular patient.When an orthopedic surgeon recommends total hip replacement surgery fora particular patient, a variety of images may be obtained utilizing CT,MRI, and other scans, such as x-rays, to generate 3D modeling of thepatient's bone structure, particularly the femur, the pelvic bone, andthe coxal (hip) bone. From such 3D models, the surgeon may determine thespecific, final location and orientation of an acetabular cup to besecured to the patient's acetabulum during surgery. Once the finallocation and orientation of the acetabular cup is determined, thesurgeon (utilizing 3D images) may create a first patient-specific jigand a second—and in some cases a third—patient-specific jig to beinserted into the patient's acetabulum during the surgery to ultimatelyachieve accurate positioning of the prosthetics to be installed in thepatient.

The first patient-specific jig may be designed and manufactured based ona first patient-specific acetabulum male portion, while the secondpatient-specific jig may be designed and manufactured based on a secondpatient-specific acetabulum male portion. The first and secondpatient-specific acetabulum male portions can be developed as eitherphysical components via a prototyping machine or visual representationsin a 3D modeling software program based upon the 3D images of thepatient. The male portion may or may not fully contact the patient'snative acetabulum.

The first patient-specific jig can be a hemispherical shaped device or asub-hemispherical shaped device, and can be comprised of compositematerial or other materials. The first patient-specific jig may includeat least three alignment members for attachment to specific portions ofthe jig based on the specific bone structure of the patient's coxalbone. The at least three alignment members may assist with properalignment of the first patient-specific jig in the patient's acetabulumduring surgery. The three alignment members may include first, second,and third alignment members that are positioned at specific outerportions of the first patient-specific jig.

In some embodiments, the first, second, and third alignment members aredesigned and adapted to be hooked on or engaged with (or otherwisepositioned at) particular portions of the coxal bone adjacent to theacetabulum to stabilize and properly orient the first patient-specificjig into the acetabulum during surgery. The first alignment member maybe positioned on the first patient-specific jig to engage a particularportion of the medial rim of the acetabulum of the coxal bone. Thesecond alignment member may be positioned on the first patient-specificjig to engage a particular portion of the greater sciatic notch of thecoxal bone. The third alignment member may be positioned on the firstpatient-specific jig to engage a particular portion of the obturatorforamen of the coxal bone. These alignment members may contact any threeareas of bone peripheral to the acetabulum. Thus, the firstpatient-specific jig includes three reference points/members, specificto the patient's acetabulum of the coxal bone, to properly align thefirst patient-specific jig in the acetabulum during surgery and providefor proper orientation of the reaming machine when resurfacing theacetabulum.

The three alignment members may each comprise a pair of hooks or otherdevices that provide sufficient engagement with the particular portionsof the coxal bone, as determined by the surgeon during preoperation. Aperson having ordinary skill in the art when reviewing this disclosurewill understand that the three alignment members may be secured orremovably attached or abutted to the first patient-specific jig by anycurrently or later known suitable means or attachment methods. The threealignment members may pivot, swivel or otherwise move relative to thefirst patient-specific jig, or they may be relatively immovable orinflexible to provide sufficient force against respective portions ofthe coxal bone to ensure proper orientation of the firstpatient-specific jig.

An aperture may be provided radially into or through the firstpatient-specific jig. The aperture is adapted to receive a guide pin orpost extension through the aperture during surgery. The guide pin orextension is placed into the aperture and is removably secured to thecoxal bone of the patient in a particular orientation and at aparticular depth, as determined by the surgeon during preoperation. Thefirst patient-specific jig is then removed while the guide post remainspositioned in the coxal bone at the desired angle and position. Theguide post may then serve as a guide for the reaming machine toaccurately ream (resurface) the acetabulum to a predetermined depth andorientation for receiving the acetabular cup. The guide post and thereamer may have the same or similar central axes, as with conventionalreaming machines and processes. In some embodiments the guide post maybe removed prior to reaming and a surgeon at his discretion may use theguide post sinus tract as a guide to reaming without the guide post at adesired angle and to a desired depth.

As discussed above, it is critical to ream the acetabulum accurately andas determined during preoperation. Accordingly, the secondpatient-specific jig may be provided to assist in determining accuratereaming and proper alignment of the acetabular cup before the cup isimplanted into the patient's acetabulum. As indicated below, a thirdpatient-specific jig may also be used to progressively prepare theacetabulum to properly receive the prosthetic acetabular cup.

The second patient-specific jig may be designed and manufactured basedon the second patient-specific male portion, but it may also be based onthe first patient-specific male portion. The second patient-specific jigmay include at least three alignment members, which may be based on thesame or similar positions as the first, second, and third alignmentmembers of the first patient-specific jig, or the positions may bedifferent depending upon the patient's anatomy. The secondpatient-specific jig may also include an aperture having the same orsimilar position and orientation as the aperture in the firstpatient-specific jig, or it may be different. The secondpatient-specific jig may also have an axial length that is greater thana corresponding axial length of the first patient-specific jig due tothe fact that the second patient-specific jig is utilized after some orall of the reaming of the acetabulum has occurred.

After the surgeon has removed the first patient-specific jig and reamedthe acetabulum to a predetermined depth and orientation, the reamerdevice is removed from the acetabulum and the guide post may remainattached to the coxal bone or, in some instances, may be removed. Thesurgeon may then position the second patient-specific jig into thereamed acetabulum without a pin or, alternatively, onto the originalguide pin or post extension, or alternatively over a different pin orpost extension used to align the second patient-specific jig. Using theparticular shape and size of the second patient-specific jig and, whereapplicable, the alignment of the aperture through the jig, the surgeonmay then rotate and position the second patient-specific jig in thereamed acetabulum to determine whether additional reaming is required inone or more quadrants, or whether the acetabulum has been reamedaccurately to receive the prosthetic acetabular cup. In furtherance ofsuch determination, the surgeon may also utilize the alignment membersattached to the second patient-specific jig, if they were designed andmanufactured for attachment to the jig; it may be that the aperture andthe shape of the second patient-specific jig is sufficient for purposesof accurate alignment of the prosthetic acetabular cup.

In some instances, if adequate remaining in any direction has not beenaccomplished and confirmed with only one or two jigs, there may be aneed for additional reaming after which a third jig may be used. Thethird patient specific jig may be similar or different in regards toalignment members and guide post aperture orientation as the firstand/or second patient specific jigs.

Once accurate reaming is accomplished through utilizing some or all ofthe above described devices and methods, the surgeon may then implant orsecure the acetabular prosthetic cup to the reamed acetabulum in atraditional manner, such as with or without screws and with or withoutcement and with or without use of a guide pin or post extension.

The predetermined orientation of the apertures and the alignment membersof both the first and second (and, as applicable, third)patient-specific jigs may provide the surgeon with a quick, accuratemeans to properly resurface the acetabulum without the use of additionaldevices and machines. This is possible because the positions of thealignment members of the first, second and third patient-specific jigsare based upon the patient's bone structure, thereby providing threereference points to accurately utilize the first jig, the guide post,the reamer, and the second and third jigs, as planned duringpreoperation based upon the 3D modeling images of the patient, acombination of two-dimensional radiographic images of the patient, or acombination of three-dimensional and two-dimensional images of apatient.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIGS. 1-4 are flow diagrams illustrating steps for pre-operative imagingand planning for a joint replacement procedure, according to an aspectof the present invention.

FIG. 4A schematically illustrates a system for carrying out the steps ofFIGS. 1-4.

FIGS. 5 and 6 are flow diagrams illustrating steps for performing ajoint replacement procedure, according to an aspect of the presentinvention.

FIG. 7 is a front view of a pelvic bone.

FIG. 8 is a top view of a prosthetic implant seated in the pelvic boneof FIG. 7.

FIG. 9A is a top view of a patient-specific jig mounted on the pelvicbone of FIG. 7 according to one embodiment.

FIG. 9B is a partial cross-sectional view of the pelvic bone of FIG. 7and a side view of the patient-specific jig of FIG. 9A.

FIG. 10A is an isometric view of a first patient-specific jig accordingto one embodiment.

FIG. 10B is an elevational view of the first patient-specific jig ofFIG. 10A.

FIG. 11A is an isometric view of a second patient-specific jig accordingto one embodiment.

FIG. 11B is an elevational view of the second patient-specific jig ofFIG. 11A.

FIG. 12A is an isometric view of a third patient-specific jig accordingto one embodiment.

FIG. 12B is an elevational view of the third patient-specific jig ofFIG. 8.

FIG. 13A is a side view of a first patient-specific jig positioned in anacetabulum and a guide post positioned through said jig and secured tothe acetabulum.

FIG. 13B is a side view of the pelvic bone showing the firstpatient-specific jig positioned in the acetabulum.

FIG. 14 is a cross-sectional view of a reaming tool positioned in theacetabulum.

FIG. 15A is a side view of a second patient-specific jig positioned inan acetabulum and a supplemental guide post positioned through said jigand secured to the acetabulum.

FIG. 15B is a side view of the pelvic bone showing the secondpatient-specific jig positioned in the acetabulum 15A.

FIG. 16 is a cross-sectional view of a reaming tool positioned in theacetabulum.

FIG. 17A is a side view of a third patient-specific jig positioned inthe acetabulum and the supplemental guide post of FIG. 15A.

FIG. 17B is a top view of the third patient-specific jig positioned inthe acetabulum as shown in FIG. 17A.

FIG. 18 is an isometric view of an impactor tool used to install aprosthetic implant in a reamed acetabulum according to one aspect of thepresent disclosure.

FIG. 19 is an isometric view of a cannulated acetabular impactoraccording to an embodiment of the present invention.

FIG. 20 is an end view of the cannulated acetabular impactor of FIG. 19.

FIG. 21 is a partial cross-sectional view of a prosthetic implant in areamed acetabulum that is being installed with the impactor tool of FIG.18 and the cannulated acetabular impactor of FIG. 19, according to oneaspect of the present disclosure.

FIG. 22 is a cross-sectional view of a portion of another cannulatedacetabular impactor according to an alternate embodiment of theinvention.

FIG. 23A is a perspective view of a patient specific jig.

FIG. 23B is a cross-sectional view of the patient specific jig of FIG.23A.

FIG. 24A is a perspective view of a patient specific jig.

FIG. 24B is a cross-sectional view of the patient specific jig of FIG.24A.

FIG. 25A is a perspective view of a patient specific jig.

FIG. 25B is a cross-sectional view of the patient specific jig of FIG.25A.

FIG. 25C is a perspective view of an outer component of the patientspecific jig of FIG. 25A

FIG. 25D is a perspective view of an inner component of the patientspecific jig of FIG. 25A

FIG. 26A is a side elevation view of a cannulated impactor.

FIG. 26B is a cross-sectional view of cannulated impactor of FIG. 26A.

DETAILED DESCRIPTION

As mentioned above, the methods and systems of the present invention arebased at least in part on pre-operating (pre-operative) imaging and atleast in part on orthopedic surgical procedures based upon thepre-operative methods and systems. As is understood in the art,pre-operative imaging has a number of different purposes and generallyis performed in order to subsequently guide the surgeon during thesurgical procedure, allow for patient-specific tools and/or implants tobe formed, etc. The present disclosure is part of a system for designingand constructing one or more patient-specific jigs for use in anorthopedic surgical procedure in which an acetabular component isprepared, orientated and implanted. The referenced systems and methodsare now described more fully with reference to the accompanyingdrawings, in which one or more illustrated embodiments and/orarrangements of the systems and methods are shown. Aspects of thepresent systems and methods can take the form of an entirely hardwareembodiment, an entirely software embodiment (including firmware,resident software, micro-code, etc.), or an embodiment combiningsoftware and hardware. One of skill in the art can appreciate that asoftware process can be transformed into an equivalent hardwarestructure, and a hardware structure can itself be transformed into anequivalent software process. Thus, the selection of a hardwareimplementation versus a software implementation is one of design choiceand left to the implementer. Throughout this disclosure, the term“prosthetic implant” and “acetabular component” refer to cup-shapedimplants that are installed into patients during hip replacementsurgery.

FIGS. 1-4 are flow diagrams illustrating methods pertaining topre-operative imaging and planning according to aspects of the presentinvention. FIG. 4A shows a system for carrying out the methods of thepresent disclosure, such as those described with reference to FIGS. 1-4.As a preliminary matter, FIG. 4A is a simplified system 410 of devicesthat may be used to carry out the methods of the present disclosure. Thesystem 410 comprises a computing system 412 coupled to an imaging system414 that captures and transmits patient image data to the computingsystem 412. The computing system 412 processes such data and transmitsthe data to the display device 416 for display of images and other data.An input device 418 receives input from a computer or an operator (suchas a surgeon) and transmits inputted information to the computing system412 for processing. Such systems are well known in the art and will notbe described in greater detail. The imaging system 412 may include abone imaging machine for forming three-dimensional image data from bonestructure of a patient. The computing system 412 may include apatient-specific device generator for processing and generating images,and a patient-specific device converter for generating design controldata. A manufacturing machine 420 receives the control data from thecomputing system 412 for making patient-specific various jigs.

In FIG. 1, a method 100 according to an embodiment starts at 101. At102, a bone imaging machine generates a bone surface image fromthree-dimensional image data from bone structure of a patient. At 104, apatient-specific device generator generates a prosthesis implant imagesuperimposed in an acetabulum of the bone surface image. The implant inthe image is positioned in its final, implanted position andorientation, regardless of the state of the patient's bone. The jigscreated from the present invention will be designed to modify the bonesuch that the implant will be properly positioned at the end of theprocedure.

At 106, the patient-specific device generator generates a first-patientspecific jig image superimposed proximate the acetabulum of the bonesurface image according to the installation position. At 108, apatient-specific device converter generates control data from the firstpatient-specific jig image and ends or moves to 110. At 110, thepatient-specific device generator generates a second patient-specificjig image superimposed in the acetabulum of the bone surface image andends or moves to 112. At step 112, the patient-specific device generatorgenerates a third patient-specific jig image superimposed in theacetabulum of the bone surface image and ends.

FIG. 2 shows a method 200 according to an aspect of the presentdisclosure. At 202, a patient-specific device generator generates aguide post image at least partially positioned through an acetabulum ofthe bone surface image. At 204, the patient-specific device generatorgenerates a first patient-specific jig image superimposed in theacetabulum of the bone surface image according to the installationposition. At 206, the patient-specific device generator generates anaperture image through the body image of the second patient-specific jigimage and ends.

FIG. 3 shows a method 300 according to an aspect of the presentdisclosure. At 302, a patient-specific device generator generates aguide post image at least partially positioned through an acetabulum ofthe bone surface image. At 304, the patient-specific device generatorgenerates a second patient-specific jig image superimposed in theacetabulum of the bone surface image according to the installationposition. At 306, the patient-specific device generator generates anaperture image through the body image of the first patient-specific jigimage and ends.

FIG. 4 shows a method 400 according to an aspect of the presentdisclosure. At 402, a patient-specific device generator generates aguide post image at least partially positioned through an acetabulum ofthe bone surface image. At 404, the patient-specific device generatorgenerates a third patient-specific jig image superimposed in theacetabulum of the bone surface image according to the installationposition. At 306, the patient-specific device generator generates anaperture image through the body image of the third patient-specific jigimage and ends.

As discussed above, FIG. 4A shows a system 410 for carrying out themethods of FIGS. 1-4 according to some aspects of the presentdisclosure. The computing system 412 may include instructions in theform of computer software for automatically generating images ofprosthesis implants in final installation positions on the bonestructure images and for automatically generating various guide postimages and jig images designed for use during surgery on the particularpatient. In some aspects, it may be necessary for the surgeon duringpreoperative planning to input information into the input device 418 forcreating or altering guide post and jig images for a particular patientbased on the surgeon's understanding of the particular bone structure ofthe patient as displayed on the display device 416.

FIGS. 5 and 6 are flow diagrams of methods pertaining to operativesurgery according to aspects of the present disclosure. The methods ofFIGS. 5 and 6 may be carried out by a surgeon or by a machine, or byboth. Moreover, the surgeon may utilize some or all of the devicesdiscussed with reference to FIGS. 1-4A during surgery, such as viewingthe preoperative images displayed on the display device while operatingon a patient.

In FIG. 5, a method 500 according to an aspect starts at 501. At 502, afirst patient-specific jig is positioned in an acetabulum of a patient.The first patient-specific jig is formed according to a predeterminedinstallation position of a prosthesis implant to be secured to thepatient. At 504, each of three alignment members is engaged with acorresponding pre-selected area on a coxal bone and adjacent theacetabulum of the patient. At 506, a guide post is positioned throughthe aperture of the first patient-specific jig and is secured into thecoxal bone of the patient. At 508, the first patient-specific jig isremoved from the guide post. At 510, bone material from the acetabulumis reamed with aid of a reaming machine. At 512, it is determinedwhether the reaming machine has reached an installation reference pointof the installation position; this may be determined by the surgeon orby a measuring device or other device to determine the depth of bonethat was reamed. If the reaming machine has reached an installationreference point, at 514 the guide post is removed and the prosthesisimplant is installed in the patient, then ends. If the reaming machinehas not reached an installation reference point, at 516 the guide postis removed and a second patient-specific jig is positioned in the reamedacetabulum of the patient, then to step 602 in FIG. 6. As furtherdiscussed below, in some aspects the guide post is not removed andremains secured to the patient until the prosthesis implant isinstalled.

At step 602, three alignment members of the second patient-specific jigare respectively engaged with predefined selected areas proximate theacetabulum of the patient. At 604, a supplemental guide post ispositioned through the aperture of the second patient-specific jig andis secured into the coxal bone of the patient. At 606, the secondpatient-specific jig is removed from the supplemental guide post and theacetabulum. At 608, the acetabulum is reamed with aid of a reamingmachine. In some instances the guide post can be removed prior toreaming and the sinus tract in the bone from the guide post is used as avisual guide to ream at a desired orientation and to a desired depth. At610, a third patient-specific jig is positioned in the reamed acetabulumof the patient. At 612, it is determined whether all three alignmentmembers of the third patient-specific jig are engaged to respectiveselected areas proximate the acetabulum of the patient. If yes, at 616the supplemental guide post may or may not be removed and the prosthesisimplant is secured to the reamed acetabulum and then ends. If no, themethod returns to 608 and the operations are repeated until it isdetermined that all three alignment members of the thirdpatient-specific jig are engaged to respective selected areas proximatethe acetabulum of the patient so that the prosthesis implant may beinstalled in the patient.

FIGS. 7 and 8 show an acetabular component 700 oriented an in anacetabulum 702 of a coxal bone 704 of a pelvic bone 706. The acetabularcomponent 700 is positioned according to an installation position 708,which is in part determined by a prescribed anteversion angle and aprescribed inclination angle of the acetabular component 700. FIG. 7shows a front view of the pelvic bone 706 and the acetabular component700 positioned in the acetabulum 702 of the patient's right coxal bone704, and FIG. 8 shows a lateral view of the right coxal bone 704 withthe acetabular component 700 positioned in the acetabulum 702. Thesefigures illustrate the incorporation of steps discussed with referenceto FIGS. 1-4A where the acetabular component 700 is a generated imagethat is superimposed over a generated image of bone structure (e.g., thecoxal bone 704) of a patient to determine an installation position 708of the acetabular component 700. Determining the prescribed anteversionangle and the prescribed inclination angle for a particular patientinvolves techniques and calculations that are known in the art, andthus, will not be described in detail. Although not necessarily part ofthe preoperative planning, for purposes of illustration an installationaxis P is shown on FIG. 7

Once the installation position 708 is determined, a reference point 710is established that represents a particular point in the coxal bone 704of the patient for purposes of determining the depth to which a reamingmachine will ream bone material, which will be further discussed below.The reference point 710 may be considered a point on the tangentialplane of a hemispherical shaped surface, such as the outer surface shapeof the acetabular component 700.

With continued reference to FIG. 8, the coxal bone 704 includes (amongmany others) a medial rim 712, a sciatic notch 714, and an obturatorforamen 716, which all have various shapes and surfaces that arespecific to each patient.

FIGS. 9A and 9B show a patient-specific jig 720 oriented in theacetabulum 702 of the coxal bone 704 according to the installationposition 708 of the acetabular component 702. These figures show atechnique that incorporates steps of FIGS. 1-4A in that thepatient-specific jig 720 is a generated image that is superimposed overthe generated image of the bone structure of a patient. As a preliminarymatter, the patient-specific jig 720 may be any one of the first,second, and third patient-specific jigs discussed with reference toFIGS. 10A-15B and elsewhere in this disclosure. FIGS. 9A and 9B are mereillustrations of one possible patient-specific jig 720.

The patient-specific jig 720 includes an aperture 722 and threealignment members 724 a, 724 b, 724 c. The aperture 722 is formedthrough the patient-specific jig 720 at an angle that corresponds to theinstallation position 708 of the acetabular component 700. Dependingupon the particular patient-specific jig 720 (i.e., the first, second,or third), the relative orientation of the aperture 722 may varydepending upon the required amount of bone to be removed and theparticular required angle of a reaming head during operation, which isultimately determined by the installation position 708 of the acetabularcomponent 700. The angles of the various apertures for the various jigsare discussed further below.

The three alignment members 724 a, 724 b, 724 c are attached to thepatient-specific jig 720 at positions around a circumference end 726 (ordistal end) of the patient-specific jig 720 depending upon theparticular bone structure of the particular patient. The three alignmentmembers 724 a, 724 b, 724 c may be formed integral with the jig or maybe attached to the jig with any suitable attachment means. The purposeof the three alignment members 724 a, 724 b, 724 c help the surgeon: 1)determine the proper orientation of a guide post to be installed in thepatient (FIGS. 13A and 15A), and/or 2) determine whether additionalreaming of bone is necessary before utilizing another jig or beforefinal installation of an acetabular component. In any event, dependingon whether all of the three alignment members 724 a, 724 b, 724 c of aparticular patient-specific jig 720 are in contact with respectiveselected areas of the patient's bone during surgery when the particularjig is placed in the acetabulum 702, corresponding information isconveyed to the surgeon. The surgeon will be able to determine the nextappropriate steps during surgery, as further described below.

The positions of the three alignment members 724 a, 724 b, 724 c willdepend on which particular jig (i.e., first, second, or third jigs) thethree alignment members are attached to. However, the positions thethree alignment members 724 a, 724 b, 724 c may be the same on each jigdepending on the preoperative requirements determined by the surgeon andthe computing systems. In one example and as shown on FIG. 9B, the firstalignment member 724 a is attached to the patient-specific jig 720 at anattachment portion 726 a, and the second alignment member 724 b isattached to the patient-specific jig 720 at an attachment portion 726 b,and the third alignment member 724 c is attached to the patient-specificjig 720 at an attachment portion 726 c. The position of the respectiveattachment portions 726 a, 726 b, 726 c are determined duringpre-operative imaging and planning steps. Accordingly, the threealignment members 724 a, 724 b, 724 c extend from the circumference end726 of the patient-specific jig 720 and are designed to contact certainselected areas of the coxal bone 704 depending on the bone structure ofthe patient. The first alignment member 724 a contacts a selected area728 a of the medial rim 712. The second alignment member 724 b contactsa selected area 728 b of the sciatic notch 714. Finally, the thirdalignment member 724 c contacts a selected area 728 c inferiorally belowthe transverse acetabular ligament at the superior portion of theobturator foramen 716. In some instances, such as when using the secondand third jigs, the contact between the alignment members and therespective selected areas is dependent upon whether the surgeon hasreamed enough bone. If not, at least one of the alignment members willnot be in contact with the respective selected area, indicating thatmore bone needs to be removed, as further discussed below.

FIGS. 10A and 10B show a first patient-specific jig 730. FIGS. 11A and11B show a second patient-specific jig 744. FIGS. 12A and 12B show athird patient-specific jig 754. These figures represent that thepatient-specific jigs are generated images based on the installationposition of the acetabulum component and based on the bone structure ofthe patient. Some or all of the patient-specific jigs are formed by amachine based on the generated images, as further discussed elsewhere inthis disclosure. In some cases, only a first patient-specific jig isgenerated and created in instances where very little bone reaming isrequired, for example. In other instances, only a second or only a thirdpatient-specific jig is utilized to accurately guide placement of anacetabular component without using the patient specific jig(s) to assistwith removal of acetabular bone.

FIG. 10A shows an isometric view of a first patient-specific jig 730 andFIG. 10B shows a side elevational view of FIG. 10A. The firstpatient-specific jig 730 includes three alignment members 732 a, 732 b,732 c that extend from a circumference end 734 of the firstpatient-specific jig 730 at positions to contact certain selected areasof the coxal bone (see FIG. 9A (generically) and FIG. 13B(specifically)). The first alignment member 732 a is attached to thepatient-specific jig 730 at an attachment portion 736 a, and the secondalignment member 732 b is attached to the first patient-specific jig 730at an attachment portion 736 b, and the third alignment member 732 c isattached to the patient-specific jig 730 at an attachment portion 736 c.The angle and position of each alignment member 732 a, 732 b, 732 crelative to the circumference end 734 is determined according to theparticular position and surface of the selected areas of the coxal boneof the patient that the alignment members 732 a, 732 b, 732 c aredesigned to contact during use of the first patient-specific jig 730during operation. Each alignment member 732 a, 732 b, 732 c includes anengagement portion 738 a, 738 b, 738 c, respectively, which is theportion of the alignment member that contacts respective selected areasof the coxal bone 704. See FIGS. 13A and 13B for illustrations of theposition of each alignment members 732 a, 732 b, 732 c relative to thefirst patient-specific jig 730 and the selected areas of the patient'scoxal bone 704.

The first patient-specific jig 730 includes an aperture 740 that extendsfrom a reference end 742 to the circumference end 734 of the firstpatient-specific jig 730. The aperture 740 is sized and configured toreceive a guide post positioned in a patient (FIG. 13A). As furtherdescribed below, the guide post is positioned according to theinstallation position 708 of the acetabular component 700 (FIGS. 7 and8). The first patient-specific jig 730 includes a height H1, which isselected so that the reference end 742 does not contact an unreamedacetabulum at the beginning stages of surgery. This is discussed furtherbelow.

FIG. 11A shows an isometric view of a second patient-specific jig 744and FIG. 11B shows a side elevational view of FIG. 11A. The secondpatient-specific jig 744 includes three alignment members 746 a, 746 b,746 c that extend from a circumference end 748 of the secondpatient-specific jig 744 at positions to contact certain selected areasof the coxal bone (see FIG. 9A (generically) and FIG. 15B(specifically)). The alignment members 746 a, 746 b, 746 c are attachedto the second patient-specific jig 744 at respective attachment portions750 a, 750 b, 750 c, similar to the first patient-specific jig 730. Theangle and position of each alignment member 746 a, 746 b, 746 c relativeto the circumference end 748 is determined according to the particularposition and surface of the selected areas of the coxal bone of thepatient that the alignment members 746 a, 746 b, 746 c are designed tocontact during use of the second patient-specific jig 744 duringoperation. The angle and position of each alignment member 746 a, 746 b,746 c may be the same as or different than that of the alignment membersof the first patient-specific jig 730 of FIG. 10A. Each alignment member746 a, 746 b, 746 c includes an engagement portion 748 a, 748 b, 748 c,respectively, which is the portion of the alignment member that contactsrespective selected areas of the coxal bone 704. See FIGS. 15A and 15Bfor illustrations of the position of each alignment member 746 a, 746 b,746 c relative to the second patient-specific jig 744 and the selectedareas of the patient's coxal bone 704.

The second patient-specific jig 744 includes an aperture 750 thatextends from a reference end 752 to the circumference end 748 of thesecond patient-specific jig 744. The aperture 750 is sized andconfigured to receive a supplemental guide post positioned in a patient(FIG. 15A). As further described below, the supplemental guide post ispositioned according to the installation position 708 of the acetabularcomponent 700 (FIGS. 7 and 8). The second patient-specific jig 744includes a height H2, which is selected so that, if the reference end752 contacts a reamed acetabulum, and if at least one of the alignmentmembers 746 a, 746 b, 746 c is not in contact with a respective selectedarea of the coxal bone, the surgeon will know that additional reaming isnecessary before installing the supplemental guide post and placing thefinal acetabular prosthesis. This is discussed further below.Understandably, height H2 can be greater than height H1, in part becausebone is reamed between usage of the first and second jigs.

FIG. 12A shows an isometric view of a third patient-specific jig 754 andFIG. 12B shows a side elevational view of FIG. 12A. The thirdpatient-specific jig 754 includes three alignment members 756 a, 756 b,756 c that extend from a circumference end 758 of the thirdpatient-specific jig 754 at positions to contact certain selected areasof the coxal bone (see FIG. 9A (generically) and FIG. 17B(specifically)). The alignment members 756 a, 756 b, 756 c are attachedto the third patient-specific jig 754 at respective attachment portions760 a, 760 b, 760 c, similar to the first patient-specific jig 730. Theangle and position of each alignment member 756 a, 756 b, 756 c relativeto the circumference end 758 is determined according to the particularposition and surface of the selected areas of the coxal bone of thepatient that the alignment members 756 a, 756 b, 756 c are designedcontact during use of the third patient-specific jig 754 duringoperation. The angle and position of each alignment member 756 a, 756 b,756 c may be the same or different to that of the alignment members ofthe first and second patient-specific jigs of FIGS. 10A and 11A. Eachalignment member 756 a, 756 b, 756 c includes an engagement portion 762a, 762 b, 762 c, respectively, which is the portion of the alignmentmember that contacts respective selected areas of the coxal bone 704.See FIGS. 17A and 17B for illustrations of the position of eachalignment members 756 a, 756 b, 756 c relative to the thirdpatient-specific jig 754 and the selected areas of the patient's coxalbone 704.

The third patient-specific jig 754 includes an aperture 764 that extendsfrom a reference end 766 to the circumference end 758 of the thirdpatient-specific jig 754. The aperture 764 is sized and configured toreceive the supplemental guide post positioned in a patient (FIG. 17A).As further described below, the supplemental guide post is positionedaccording to the installation position 708 of the acetabular component700 (FIGS. 7 and 8). The third patient-specific jig 754 includes aheight H3, which is selected so that, if the reference end 766 contactsa reamed acetabulum, thereby causing at least one of the alignmentmembers 756 a, 756 b, 756 c to not be in contact with a respectiveselected area of the coxal bone, the surgeon will know that additionalreaming is necessary before installing the acetabular component 700 inthe patient. This is discussed further below. Understandably, height H3can be greater than height H2 because bone is reamed between usage ofthe second and third jigs, and because the second patient-specific jigis used for purposes of positioning the supplemental guide post whilethe third patient-specific jig is used for purposes of determiningwhether additional reaming is necessary before installing the acetabularcomponent 700 in the patient.

It will be appreciated that each or all of the alignment members of anyone of the patient-specific jigs may be formed in various configurationand shapes. For example, an alignment member may be an arc shaped orother non-linear shaped member, or it may have two or more anglessurfaces. The exact shape, position, and alignment of each alignmentmember is determined by the surgeon and the computing system duringpreoperative planning depending upon the specific bone structure of thepatient and the installation position of the acetabulum component.

FIGS. 13A and 13B show the first patient-specific jig 730 positioned inan un-reamed acetabulum 703 of the patient, and FIG. 14 shows a reamingtool 768 positioned in the acetabulum 703 and ready to ream bonematerial. These figures show a technique that incorporates thepreoperative steps of FIGS. 1-4A in that the first patient-specific jig730 and a guide post 770 are generated images that are superimposed overthe generated image of the bone structure of a patient. These figuresalso show a technique that incorporates the operative steps practiced bya surgeon on a patient, such as described with reference to FIGS. 5 and6.

During preoperative planning and with reference to FIGS. 9A and 9B, agenerated image of an acetabular component 700 is imposed over the bonestructure image, which ultimately shows the installation position 708 ofthe acetabular component 700. Based on such installation position 708,the computer system determines, with input from the surgeon, the exactposition of the guide post 770 to be installed in the patient duringearly stages of operation. The guide post 770 will be the guide for theposition of the first patient-specific jig 730 and the reaming machine768. Preferably, the guide post 770 is positioned substantiallyperpendicular to a central axis of the acetabular component 700 to belater installed in the patient; however, the angle of the guide post 770relative to the acetabular component 700 may vary depending upon thepreoperative surgery analysis by the computer system and the surgeonbased on patient requirements. Once the orientation of the guide post770 is established and displayed as a generated image, an image isgenerated of the first patient-specific jig 730. As noted above, thepurpose of the first patient-specific jig 730 is to establish the exactposition of the guide post 770 to be installed in the patient duringsurgery. Accordingly, the reference end 742 of the firstpatient-specific jig 730 is designed to make contact with the un-reamedacetabulum 703. The three alignment members 732 a, 732 b, 732 c aredesigned to contact respective selected areas of the coxal bone 704adjacent the acetabulum 703.

With particular reference to FIG. 13B, during surgery the surgeoninserts the first patient-specific jig 730 into the acetabulum 703 androtates or otherwise orients the first patient-specific jig 730 in thepatient until all three alignment members 732 a, 732 b, 732 c are incontact with respective selected areas 772 a, 772 b, 772 c of the coxalbone 704. Once the first patient-specific jig 730 is properly oriented,the surgeon inserts the guide post 770 through the aperture 740 andguide post 770, which may be a threaded pin, and may be drilled into thebone (typically 2 mm to 20 mm deep). Thus, the guide post 770 will beinstalled at the exact position determined during preoperative planningand according to the installation position of the acetabular component700. The first patient-specific jig 730 may then be removed and areaming machine 768 may be used to remove bone material from thepatient, either over the guide post or without it in place.

FIG. 14 illustrates the reaming machine 768 used for such purpose. Thereaming machine 768 includes a reaming head 774, which may be adetachable head of a selected size corresponding to the size of theacetabular component 700 to be installed. The reaming head 774 includesa guide aperture 776 that slidably receives the guide post 770. Thereaming head 774 reams bone with a consistent axial motion in adirection depicted by Arrow A because the guide aperture 776 includes acentral axis coextensive with a central axis of the guide post 770 andbecause the guide aperture 776 closely receives the guide post 770. Insome embodiments, the reaming may be cannulated while in otherembodiments, the reaming may not be cannulated. In some embodiments, Thesurgeon may remove the guide post prior to reaming and use the visiblepilot hole as a visual guide to center the reamers that can be used bytraditional means without cannulated reaming. Such reaming heads with aguide aperture and methods of using such reaming heads with a guide postin a patient are well known in the art and will not be described ingreater detail.

FIGS. 15A and 15B show the second patient-specific jig 744 positioned ina reamed acetabulum 705 of the patient, and FIG. 16 shows a reaming tool768 ready to ream additional bone material. These figures show atechnique that incorporates the preoperative steps in that the secondpatient-specific jig 744 is a generated image that is superimposed overthe generated image of the bone structure of a patient. These figuresalso show a technique that incorporates the operative steps practiced bya surgeon on a patient.

FIG. 15A shows the reamed acetabulum 705 as the result of the surgeonreaming a portion of the acetabulum 703 to a desired depth. In someinstances, the surgeon will ream a couple millimeters of bone and willhave reached the reference point 710 (FIG. 7) such that bone reaming iscompleted and the acetabular component 700 can be installed in thepatient. In other instances, additional bone reaming is necessary to adepth depending upon the installation position 708 for a particularpatient as determined during preoperative planning. When it isdetermined that additional bone reaming is necessary, in some instancesthe guide post 770 of FIG. 13A remains installed in the patient and thesecond patient-specific jig 744 is utilized to determine if additionalbone reaming is necessary; this is accomplished by inserting the secondpatient-specific jig 744 into the reamed acetabulum 705. In someembodiments, the second patient-specific jig 744 is inserted over theguide post 770 while in other embodiments, the guide post 770 may beremoved before inserting the second patient specific jig 774. With thesecond patient specific jig in the acetabulum 705, the surgeon maydetermine whether the three alignment member 746 a, 746 b, 746 c are allin contact with selected areas 772 a, 772 b, 772 c of the coxal bone704. If not, in some embodiments, before further reaming, the surgeonmay reinsert the guide post 770 into the bone and advance it or drill itfurther into the bone. The surgeon may then remove the guide post 770and may utilize the reaming machine 768 of FIG. 14 and ream additionalbone material. The surgeon may continue to check the depth of the reamedacetabulum 705 by utilizing the second patient-specific jig 744 as notedabove until all three alignment members 746 a, 746 b, 746 c are incontact with the selected areas 772 a, 772 b, 772 c of the coxal bone704. Once this is achieved, the surgeon will know with accurateprecision that the reference point 710 has been reached and at thedesired angle for accurate installation of the acetabular component 700in the patient. The surgeon may then install the acetabular component700 in the patient utilizing known techniques in the art. In the currentmethod, a guide post may be utilized over which the acetabular component700 may be more accurately placed than with standard techniques.

In other instances and where additional bone reaming is necessary but ata different angle than with respect to FIG. 14 according to preoperativeplanning, the guide post 770 is removed from the patient and asupplemental guide post 778 is installed in the patient to guide thereaming machine 768 at a different angle than the original guide post770. In some instances the supplemental guide post 778 may be removedprior to reaming and the sinus tract in bone may guide the surgeon toream at an appropriate angle and to an appropriate depth. Such operativesteps are determined by the surgeon, with the use of the computingsystem, during preoperative planning. For purposes of illustration andas one example, FIGS. 15A and 15B show the supplemental guide post 778installed in the patient at a different angle than the guide post 770 ofFIGS. 13A and 14. Accordingly, once the bone is reamed as described withreference to FIG. 14, the guide post 770 is removed and the secondpatient-specific jig 744 is placed into the reamed acetabulum 705.Similar to the first patient-specific jig 730, the secondpatient-specific jig 744 is utilized to determine the orientation of thesupplemental guide post 778 to be installed in the patient. Thus, thesurgeon inserts the second patient-specific jig 744 into the reamedacetabulum 705 and rotates or otherwise orients the secondpatient-specific jig 744 in the patient until all three alignmentmembers 746 a, 746 b, 746 c are in contact with respective selectedareas 772 a, 772 b, 772 c of the coxal bone 704, as depicted on FIGS.15A and 15B. Once the second patient-specific jig 744 is properlyoriented, the surgeon inserts the supplemental guide post 778 throughthe aperture 750 and the threads of the supplemental guide post 778engage the bone. Thus, the supplemental guide post 778 will be installedat the exact position determined during preoperative planning andaccording to the installation position of the acetabular component 700.The second patient-specific jig 774 may then be removed and a reamingmachine 768 may be used to remove additional bone material from thepatient, with or without the guide post in place.

FIG. 16 illustrates the reaming machine 768 used for such purpose. Thereaming machine 768 includes a supplemental reaming head 780, which maybe a detachable head of a selected size corresponding to the size of theacetabular component 700 to be installed. The supplemental reaming head780 may be smaller in size than the reaming head 774 of FIG. 14, or itmay be the same size. The supplemental reaming head 780 may include aguide aperture 782 that slidably receives the supplemental guide post778. The supplemental reaming head 780 reams bone with a consistentaxial motion in a direction depicted by Arrow B because the guideaperture 782 includes a central axis coextensive with a central axis ofthe supplemental guide post 778 and because the guide aperture 782closely receives the supplemental guide post 778. Such reaming headshaving a guide aperture are well known in the art and will not bedescribed in greater detail.

FIGS. 17A and 17B show the third patient-specific jig 754 positioned ina reamed acetabulum 707 of the patient. These figures show a techniquethat incorporates the preoperative steps of FIGS. 1-4A in that the thirdpatient-specific jig 754 is a generated image that is superimposed overthe generated image of the bone structure of a patient. These figuresalso show a technique that incorporates the operative steps practiced bya surgeon on a patient disclosed herein.

FIG. 17A shows a reamed acetabulum 707 as the result of the surgeonreaming a portion of the acetabulum 705 to a desired depth, as discussedwith reference to FIG. 16. In some instances, the surgeon will ream oneor two millimeters of bone and utilize the third patient-specific jig754 to determine whether additional bone reaming is necessary beforefinal installation of the acetabular component in the patient, asdetermined during preoperative planning. Thus, the surgeon inserts thethird patient-specific jig 754 into the reamed acetabulum 707. If allthree alignment members 756 a, 756 b, 756 c are in contact withrespective selected areas 784 a, 784 b, 784 c of the coxal bone 704,then the third patient-specific jig 754 has indicated that the referencepoint 710 of the installation position 708 has been reached, andtherefore, bone reaming is completed.

The surgeon will then install the acetabular component 700 according toknown techniques or over a supplemental guide post using a cannulatedacetabular impactor and mallet device as described herein. For purposesof discussion, FIG. 17A shows that alignment member 756 b is not incontact with the selected area 784 b adjacent to the native acetabulum.As such, the illustrated third patient-specific jig 754 indicates thatthe reference point 710 has not been reached, and, therefore, additionalbone reaming is necessary. Accordingly, the surgeon reams bone with thereaming head 780, utilizing the supplemental guide post 778 pilot holeor sinus tract from the removed guide post as a guide member, and theninserts the third patient-specific jig 754 to determine whether allthree alignment members 756 a, 756 b, 756 c are in contact with thecoxal bone 704 and the reference point 710 (FIG. 7) has been reached bythe supplemental reaming head 780. These processes continue until theacetabulum is reamed to the desired depth of the reference point, atwhich point the surgeon installs the acetabular component 700 in thepatient, as shown on FIG. 8.

FIGS. 18-22 show aspects of the present disclosure in which an impactortool 800 is used to assist with installation of an acetabular component700 in a reamed acetabulum 705 or 707. Typically, a reamed acetabulum isreamed to have a radius slightly smaller than the radius of theacetabular component for a tight fit configuration. As such, the surgeontypically utilizes a mallet or other tool to impact the acetabularcomponent into its final position.

The impactor tool 800 includes a head 802 and a handle 804. The head 802includes a guide aperture 806 having a central axis X. During surgeryand once the acetabulum is reamed to a desired depth, the acetabularcomponent 700 is partially inserted into the reamed acetabulum. Anelongated guide post 808 is installed in the coxal bone 704 and extendsthrough a hole in the acetabular component 700, as known in the art. Acannulated acetabular impactor device 810 includes a cannulated channel812 that receives the elongated guide post 808; the cannulatedacetabular impactor device 810 may be threaded or slidably received overthe elongated guide post 808. The cannulated acetabular impactor device810 includes a distal end 814 biased against the cup portion of theacetabular component 700, and a proximal end 816 with a surface 818 tobe impacted by the impactor tool 800. The distal end of the cannulatedimpactor tool may be cylindrical, hemispherical, or any other shape. Thedistal end may simply abut the acetabular prosthesis or alternativelythread into the acetabular prosthesis. The distal end of the impactortool may be one piece or more than one piece. The guide aperture 806 ofthe impactor tool 800 slidably receives a portion of the guide post 808.The proximal portion of an impactor tool may have a cannulated openingfor the guide post in some embodiments. In some embodiments, theproximal portion of the impactor tool may not have a cannulated opening.The proximal portion of an impactor tool may be one piece or more thanone piece.

During installation of the acetabular component 700, the surgeon holdsthe handle 804 and slidably engages the guide aperture 806 of theimpactor tool 800 with the guide post 808. The surgeon then repeatedlyimpacts the surface 818 of the proximal end 816 of the cannulatedacetabular impactor device 810 with the impactor tool 800, causing animpacting force against the acetabular component 700, until theacetabular component 700 is in its final position. Typically severalimpacts with the impactor tool 800 will suffice, and typically thesurgeon can hear when the acetabular component 700 is seated flushagainst the acetabulum in its final position. One advantage of theimpactor tool 800 is that impact against the elongated member 810 (andultimately the acetabular component 700) occurs at approximately thesame impact location upon each repeated impact with the tool 800.Typically, the surgeon uses a mallet or hammer without the assistance ofany guidance, which can result in improper installation of theacetabular component 700. The guide aperture 806 of the impactor tool800 ensures repeatable impact location and position of the impactor tool800, which reduces or eliminates the possibility for human error duringrepeated impacts with a mallet or hammer.

According to an alternate embodiment, FIGS. 23A and 23B show a firstpatient-specific jig 900; FIGS. 24A and 24B show a secondpatient-specific jig 1000; and FIGS. 25A and 25B show a thirdpatient-specific jig assembly 1100. These figures showcomputer-generated images that represent the patient-specific jigs. Theyare created based on the installation position of the acetabulumcomponent and the bone structure of the patient. Some of the informationfor generating the patient-specific jigs may be derived from datagathered using two-dimensional and/or three-dimensional imagingtechniques.

The physical patient-specific jigs can be formed based on the generatedimages, as further discussed elsewhere in this disclosure. In somecases, only a first patient-specific jig is generated and created; forexample, in instances where very little bone reaming is required. Insome embodiments, physical jigs are created using a machining process,such as, an additive manufacturing process, a subtractive process, or acombination of additive and subtractive manufacturing processes.

FIG. 23A shows an isometric view of a first patient-specific jig 900;and FIG. 23B shows a cross-sectional view of a first patient-specificjig 900. The first patient-specific jig 900 may include three alignmentmembers 905 a, 905 b, 905 c that extend from a circumference end 910 ofthe first patient-specific jig 900. The alignment members are positionedto contact certain selected areas of the coxal bone (see, for example,FIG. 9A (generically) and FIG. 13B (specifically) and their associatedtext). The first alignment member 905 a is attached to thepatient-specific jig 900 at an attachment portion 906 a; the secondalignment member 905 b is attached to the first patient-specific jig 900at an attachment portion 906 b; and the third alignment member 905 c isattached to the patient-specific jig 900 at an attachment portion 906 c.The angle and position of each alignment member 905 a, 905 b, 905 crelative to the circumference end 910 is determined according to theparticular position and surface of the selected areas of the coxal boneof the patient that the alignment members 905 a, 905 b, 905 c contactduring a procedure. Each alignment member 905 a, 905 b, 905 c includesan engagement portion 904 a, 904 b, 904 c, respectively, that contactsthe coxal bone.

The engagement portion 904 a of the first alignment member 905 a may becontoured or shaped to abut the surface of the medial rim of thepatient; the engagement portion 904 b of the second alignment member 905b may be contoured or shaped to abut the surface of the sciatic notch ofthe patient; and the engagement portion 904 c of the third alignmentmember 905 c may be contoured or shaped to abut the surface of theacetabular notch of the patient. The angle A between the first alignmentmember 905 a and the second alignment member 905 b may be approximately105 degrees; the angle B between the second and third alignment members905 b, 905 c may be approximately 120 degrees; and the angle C betweenthe third and first alignment members 905 c, 905 a may be approximately135 degrees. See FIGS. 13A and 13B for exemplary illustrations of theposition of alignment members relative to a first patient-specific jigand the selected areas of a patient's coxal bone.

The first patient-specific jig 900 can include an aperture 925 thatextends from a reference end 920, through a collar 926, to a distal endof the first patient-specific jig 900. The illustrated aperture 925 issized and configured to receive a guide post positioned in a patient(for example, as shown in FIG. 13A and described in the associatedtext). The collar 926 may be supported by one or more supports, such assupport 927, which may extend from the collar 926 to the circumferenceof the jig. As further described below, the guide post is positionedaccording to an installation position, for example, installationposition 708 of the acetabular component 700 (FIGS. 7 and 8). The firstpatient-specific jig 900 includes a height h1, which may be selected sothat the reference end 920 may not contact an unreamed acetabulum at thebeginning stages of surgery. In some embodiments, the reference end 920may not contact the undreamed acetabulum. This is discussed furtherbelow.

FIG. 24A shows an isometric view of a second patient-specific jig 1000and FIG. 24B shows a cross-sectional view of the second patient-specificjig 1000. The second patient-specific jig 1000 includes three alignmentmembers 1005 a, 1005 b, 1005 c that extend from a circumference end 1010of the second patient-specific jig 1000 at positions selected to contactcertain areas of the coxal bone (see, for example, FIG. 9A (generically)and FIG. 15B (specifically) and accompanying text). The alignmentmembers 1005 a, 1005 b, 1005 c are attached to the secondpatient-specific jig 1000 at respective attachment portions 1006 a, 1006b, 1006 c, similar to the first patient-specific jig 900. The angle andposition of each alignment member 1005 a, 1005 b, 1005 c relative to thecircumference end 1010 is determined according to the particularposition and surface of the selected areas of the coxal bone or otheranatomy or anatomic structure of the patient that the alignment members1005 a, 1005 b, 1005 c are designed to contact during use of the secondpatient-specific jig 900. The angle and position of each alignmentmember 1005 a, 1005 b, 1005 c may be the same as or different than thatof the alignment members of the first patient-specific jig 900. Eachalignment member 1005 a, 1005 b, 1005 c includes an engagement portion1004 a, 1004 b, 1004 c, respectively, that contacts selected areas of acoxal bone. For example, see FIGS. 15A and 15B for illustrations of theposition of alignment members relative to a second patient-specific jigand selected areas of a patient's coxal bone.

The second patient-specific jig 1000 can include an aperture 1025 thatextends from a reference end 1020 through a collar 1026, to a distal endof the collar 1026 of the first patient-specific jig 1000. Theillustrated aperture 1025 is sized and configured to receive asupplemental guide post positioned in a patient (see, for example, FIG.15A). The collar 1026 may be supported by one or more supports, such assupport 1027, which may extend from the collar to the circumference ofthe jig. The supplemental guide post may be positioned according to theinstallation position of the acetabular cup. The second patient-specificjig 1000 includes a height h2, which is selected so that, if thereference end 1020 contacts a reamed acetabulum, or if at least one ofthe alignment members 1005 a, 1005 b, 1005 c is not in contact with arespective selected area of the coxal bone, the surgeon will know thatadditional reaming is necessary before installing the supplemental guidepost and placing the final acetabular prosthesis. This is discussedfurther below. Understandably, height h2 can be greater than height h1,in part because bone is reamed between usage of the first and secondjigs.

The reaming process may cause undercuts to develop in the acetabulum. Anundercut occurs when the reamer removes material from the interior ofthe acetabulum and cuts underneath other areas of the coxal, forexample, beneath the acetabular margin. If a jig is created to fitagainst the entire reamed surface of the acetabulum, it would not fit.Therefore, the second patient-specific jig 1000, and other jigs, inparticular jigs for use after reaming, may include a cutout 1030 thatdoes not closely match the surface of the reamed acetabulum, permittingeasy installation and removal of the jig from an acetabulum and, inparticular, a reamed acetabulum.

FIG. 25A shows an isometric view of a third patient-specific jigassembly 1100 and FIG. 25B shows a cross-sectional view thereof. Thethird patient-specific jig 1100 includes two components: an outercomponent 1101 and an inner component 1102. The outer component 1101 ofthe third patient-specific jig 1100 includes three alignment members1105 a, 1105 b, 1105 c that extend from a circumference end 1110 of thethird patient-specific jig 1100 at positions selected to contact certainareas of the coxal bone (see, for example, FIG. 9A (generically) andFIG. 17B (specifically)). As best shown in FIG. 25C, the alignmentmembers 1105 a, 1105 b, 1105 c are attached to the thirdpatient-specific jig 1100 at respective attachment portions 1106 a, 1106b, 1106 c, similar to the first patient-specific jig 900. The angle andposition of each alignment member 1105 a, 1105 b, 1105 c relative to thecircumference end 1110 is determined according to the particularposition and surface of the selected areas of the coxal bone of thepatient that the alignment members 1105 a, 1105 b, 1105 c are designedto contact during the operation. The angle and position of eachalignment member 1105 a, 1105 b, 1105 c may be the same or differentthan that of the alignment members of the first and secondpatient-specific jigs of FIGS. 23A and 24A. Each alignment member 1105a, 1105 b, 1105 c includes an engagement portion 1104 a, 1104 b, 1104 c,respectively, that contacts respective selected areas of the coxal bone.For example, see FIGS. 17A and 17B for illustrations of the position ofalignment members relative to a third patient-specific jig and selectedareas of a patient's coxal bone.

FIG. 25C shown the outer component 1101 and FIG. 25D shows the innercomponent 1102. The outer component 1101 of the third patient-specificjig 1100 includes an aperture 1151 that accepts the inner component1102. The aperture 1151 includes at least one, and preferably three,alignment structures or keyways 1155 a, 1155 b, 1155 c. Each alignmentkeyway 1155 a, 1155 b, 1155 c may be sized and shaped to accept one ofthe alignment structures or keys 1156 a, 1156 b, 1156 c of the interiorcomponent 1102 and can be configured to only allow the interiorcomponent 1102 to fit within the aperture 1151 in a single orientation.The depth of the keyways 1155 a, 1155 b, 1155 c and length of thealignment keys 1156 a, 1156 b, 1156 c can be sized such that when theinner component is properly fit to the outer component, the bottomsurface 1157 a, 1157 b, (1157 c, FIG. 25B) (see FIG. 25D) of eachalignment key 1156 a, 1156 b, (1156 c, not shown) contacts the shelf(1158 a, 1158 b, not shown), 1158 c (see FIG. 25C) of a respectivekeyway. The illustrated keyways and alignment keys are also sized andshaped such that when the inner component is properly fit to the outercomponent, the inner component alignment surface 1161 is flush orco-planar with the outer component alignment surface 1160. Thesefeatures provide the surgeon with an easy way to determine if thereaming is complete and that the two jig components properly fit in thejoint and with each other.

In some embodiments, the alignment structures or keyways of an outercomponent may be disposed along the circumference of an aperture of theouter component, as shown in FIG. 25A. In some embodiments the alignmentstructures may be at other locations on the outer component, forexample, displaced a distance from the circumference of the aperture ofthe outer component.

In some embodiments, the alignment structures or keys of an innercomponent may be disposed along the circumference of the innercomponent, as shown in FIG. 25B. In some embodiments the alignmentstructures may be at other locations on the inner component, forexample, displaced a distance from the circumference of the innercomponent.

The third patient-specific jig 1100 includes an aperture 1125 thatextends from a reference end 1121 to a distal end of the of the firstpatient-specific jig 1100. The aperture 1125 is sized and configured toreceive the supplemental guide post positioned in a patient (see, forexample, FIG. 17A). The collar 1126 may be supported by one or moresupports 1127 a, 1127 b, 1127 c which may extend from the collar to analignment surface 1161 of the jig. In addition to supporting the collar1126, the supports 1127 a, 1127 b, 1127 c also provide a place for asurgeon to grip and handle the interior component 1102. As furtherdescribed below, the supplemental guide post is positioned according toan installation position of the acetabular component.

The two-component design of the third patient-specific jig 1100 providesfor easy placement and removal of the jig in a reamed acetabulum. Inplacing the jig, a surgeon may first align and place the outer component1101 of the third patient-specific jig 1100 in the reamed acetabulum.The surgeon may then verify that the reference end 1120 of the outercomponent does not contact the reamed acetabulum. Then, the surgeon mayplace the inner component 1102 into the aperture 1151 of the outercomponent 1101 while aligning the alignment keys 1156 a, 1156 b, 1156 cwith the keyways 1155 a, 1155 b, 1155 c. The surgeon may then check thatthe inner component alignment surface 1161 is co-planar with the outercomponent alignment surface 1160. If they are co-planar, the reaming iscomplete. If they are not co-planar, for example, when the reference end1121 of the inner component 1102 contacts a portion of the acetabulum,the surgeon may need to conduct additional reaming.

In addition, the third patient-specific jig 1100 includes a height h3,which is selected so that the surgeon will know if additional reaming isnecessary before installing the acetabular component in the patient. Thesurgeon may know more reaming is necessary if the reference ends 1120,1121 contact a reamed acetabulum, and at least one of the alignmentmembers 1105 a, 1105 b, 1105 c is not in contact with a respectiveselected area of the coxal bone, or if the alignment surfaces 1160 and1161 are not co-planar. Understandably, height h3 can be greater thanheight h2 because bone may be reamed between usage of the second andthird jigs, and because the second patient-specific jig may be used forpurposes of positioning the supplemental guide post, while the thirdpatient-specific jig may be used for purposes of determining whetheradditional reaming is necessary before installing the acetabularcomponent in the patient.

Once the third patient-specific jig is in place and no more reaming isrequired, the surgeon may install a supplemental guide post through theaperture 1125 and into the patient.

With the guide post in place, the surgeon may remove the thirdpatient-specific jig 1100. If the third patient specific jig 1100 is asingle component, the surgeon, in removing the jig, may push against theguide post, knocking the jig out of position or out of the patientaltogether. With the two-component jig, the surgeon may remove the innercomponent 1102 by sliding it along the guide post and out of theacetabulum. The aperture 1151 of the outer component may be aligned withand/or concentric with the guide post. In some embodiments, the centralaxis of the aperture 1151 may coincide with or be parallel to thecentral axis of the guide post. In still other embodiments, the aperture1151 and inner component 1102 may be configured such that innercomponent 1102 is removed in a direction substantially parallel to thecentral axis of the guide post. With the inner component 1102 removed,the surgeon now has ample room to remove the outer component 1101 withmuch less risk of altering the position of the guide post.

The physician may then place an implant or prosthesis over the guidepost and into the acetabulum, and then use a cannulated impactor toplace the prosthetic into the jip joint.

In some embodiments, a surgeon may only use a single jig when replacinga joint. For example, a surgeon may use conventional joint replacementtechniques for the bone material removal or reaming process and then usea single patient-specific jig to confirm adequate removal of material.In some embodiments, a surgeon may use a single jig to confirm adequateremoval of bone material and to guide the placement of the finalprosthetic, for example, by guiding the installation of a guide post.Bone or other anatomic structures may be removed with reamers, burrs,rongeurs, drills or any other instrument. 26A and 26B show an embodimentof a cannulated impactor assembly. FIG. 26A shows a side view of thecannulated impactor assembly 1200. FIG. 26B shows a cross-sectional viewof the cannulated impactor assembly 1200. The cannulated impactorassembly 1200 includes a cannulated impactor 1210. The cannulatedimpactor is comprised of a shaft 1211 that joins an anvil 1213 at afirst end of the shaft 1211 with a second end 1212 configured to accepta head 1220. The second end may be a tapered, as shown in FIGS. 26A and26B. The tapered end facilitates alignment of the head 1220 with thecannulated impactor 1210.

As shown in FIG. 26B, the impactor 1210 includes a cannulated channel orcavity 1214. The cannulated channel 1214 receives a guide post 1270 forguiding the placement of an acetabular component. The cannulated channel1214 may also receive a sheath 1230. The sheath 1230 may fit within thecannulated channel 1214 and around the guide post 1270. The sheath 1230,guide post 1270, and cannulated channel 1214 may slidingly engage witheach other. In some embodiments the respective diameters of a sheath,guide post, and cannulated channel allow for 0.1 mm clearance betweenthe inner diameter of an outer part and the outer diameter of an innerpart. In some embodiments, the cannulated channel may be blind, forexample, as illustrated in FIG. 26B.

The head 1220 may include an aperture 1222 configured to slidably engagewith the sheath 1230 and/or the guide post 1270. The head 1220 mayinclude an engagement surface, such as the illustrated engagementsurface 1221, which is configured to engage with an end of a cannulatedimpactor. In the illustrated embodiment, the head 1220 has a taperedengagement surface 1221 configured to engage with the tapered second end1212 of the shaft 1211.

In some embodiments, the second end 1212 and engagement surface 1221 mayeach include complementary threads. In such an embodiment, the secondend 1212 screws into the engagement surface 1221.

The guide post 1270 may include a bone engagement end 1271. The boneengagement end my include threads for engaging the bone and retainingthe guide post 1270 in a patient's bone. In some embodiments, forexample, the embodiment shown in FIGS. 26A and 26B, the engagement end1271 may have a tapered point to engage the patient's bone.

It will be appreciated that each or all of the alignment members of anyone of the patient-specific jigs disclosed herein may be formed invarious configurations and shapes. For example, an alignment member maybe an arc shaped or other non-linear shaped member, or it may have twoor more angled surfaces. The alignment members and engagement portionsmay be parts of a continuous rim or lip that extends out from theentirety of the circumference end of a jig. The exact shape, position,and alignment of each alignment member may be determined by the surgeonand the computing system during preoperative planning depending upon thespecific bone structure of the patient and the installation position ofthe acetabulum component. Any three points adjacent to a joint, such asan acetabulum, may be used as a reference location to determine andplace a jig, a joint replacement, or an acetabulum implant in a desiredposition.

In some embodiments, a patient-specific jig may include one or morealignment members. In some embodiments, one or more alignment membersmay extend from the circumference of the jig and be contoured or shapedsuch that each alignment member may include one, two, three, or moreengagement portions each contoured or shaped to match up with arespective one, two, three, or more selected areas near the joint, forexample the coxal bone.

In some embodiments, a single alignment member may extend aroundsubstantially the entire circumference of the patient-specific jig. Indoing so, the single alignment member may include one, two, three, ormore engagement portions that are contoured or shaped to match up withan area near the joint.

In some embodiments, a single alignment member may extend around morethan 180 degrees of the circumference of the patient-specific jig. Insome embodiments, an alignment member may extend around less than 180degrees, 120-180 degrees, or 240-360 degrees of the circumference of thepatient-specific jig.

In some embodiments, a single alignment member may extend around thecircumference of a patient specific jig such that two or more engagementportions of the single alignment member are contoured or shaped to matchup with respective areas near the joint.

In some embodiments, two alignment members may extend from thecircumference of a patient-specific jig. A first alignment member mayinclude two or more engagement portions that are contoured or shaped tomatch up with a respective area near the joint. A second alignmentmember may include one or more engagement portions that are contoured orshaped to match up with a respective area near the joint. In a preferredembodiment the first and second alignment members may extend fromopposing sides of the circumference of a patient specific jig.

It will also be appreciated that although the jigs, impactors, andmethods have been descried in reference to a human hip joint, they arenot limited to those applications. The jigs, impactors, and methods arealso applicable to other joints, such as a shoulder joint, and toanimals other than humans, such as horses, dogs, apes, etc.

The various embodiments described above can be combined to providefurther embodiments. Aspects of the embodiments can be modified, ifnecessary to employ concepts of the various patents, applications andpublications to provide yet further embodiments.

These and other changes can be made to the embodiments in light of theabove-detailed description. In general, in the following claims, theterms used should not be construed to limit the claims to the specificembodiments disclosed in the specification and the claims, but should beconstrued to include all possible embodiments along with the full scopeof equivalents to which such claims are entitled. Accordingly, theclaims are not limited by the disclosure.

1. A method, comprising: positioning a first component of apatient-specific jig in an acetabulum of a patient, the patient-specificjig formed according to a predetermined installation position of aprosthesis implant to be secured to the patient, the first component ofthe patient-specific jig having a first aperture, a first alignmentmember attached at a respective position to the first component of thepatient-specific jig corresponding to the installation position of theprosthesis implant, and a first alignment structure; engaging the firstalignment member to a predefined selected area of a coxal bone adjacentthe acetabulum of the patient; positioning a second component of thepatient-specific jig in the first aperture of the first component of thepatient-specific jig and in an acetabulum of a patient, the secondcomponent of the patient-specific jig formed according to apredetermined installation position of a prosthesis implant to besecured to the patient, the second component of the component of thepatient-specific jig having a second aperture and a second alignmentstructure, the second alignment structure to engage with the firstalignment structure at a respective position corresponding to theinstallation position of the prosthesis implant; positioning a guidepost through the aperture of the second component of thepatient-specific jig and securing the guide post to the patient, theguide post positioned corresponding to the installation position of theprosthesis implant; removing the second component of thepatient-specific jig from the acetabulum in a direction substantiallyparallel to a central axis of the guide post; removing the firstcomponent of the patient-specific jig from the acetabulum.
 2. The methodof claim 1, further comprising: determining whether the acetabulum hasbeen reamed to receive a prosthetic acetabular cup; if the acetabulumhas not been reamed to receive a prosthetic acetabular cup, reaming theacetabulum; and if the acetabulum has been reamed to receive aprosthetic acetabular cup, securing the prosthesis implant to theacetabulum.
 3. The method of claim 2 wherein the step of determiningwhether the acetabulum has been reamed to receive a prostheticacetabular cup, further comprises: determining whether the firstalignment member of the first component of the patient-specific jig isengaged to the selected area proximate the acetabulum of the patient anddetermining whether the second alignment structure is engaged with thefirst alignment structure at a respective position corresponding to theinstallation position of the prosthesis implant; if the first alignmentmember of the first component of the patient-specific jig is not engagedto said selected area or the second alignment structure is not engagedwith the first alignment structure, reaming the acetabulum until thealignment member is engaged to said selected area and the secondalignment structure is engaged with the first alignment structure; andif the first alignment member is engaged to said selected area and thesecond alignment structure is engaged with the first alignmentstructure, thereby indicating information that an installation referencepoint has been reached, securing the prosthesis implant to the reamedacetabulum over the guide post, with or without the guide post in place.4. A system for use in joint replacement surgery, the system comprising:an imaging machine configured to generate imaging data corresponding toan anatomic structure of a patient; a patient-specific device generatorconfigured to generate a model of a reamed surface of the anatomicstructure of the patient and a first patient-specific jig image, thefirst patient-specific jig image including an outer component image andan inner component image; and a patient-specific device converterconfigured to generate design control data to control operation of amachine for making a first patient-specific jig that corresponds to thegenerated first patient-specific jig image, the first patient-specificjig positionable against the anatomic structure of the patient at aposition corresponding to an instillation position of a prosthesisimplant.
 5. The system of claim 4 wherein the outer component imageincludes a first alignment structure image configured to align with asecond alignment structure image of the inner component image, the firstand second alignment structure images configured such that alignment ofthe first alignment structure image with the second alignment structureimage corresponds to a final installation position of a prostheses to besecured to the anatomic structure of the patient according to theimaging data.
 6. The system of claim 5 wherein the outer component imageincludes a first alignment member image at a position on the outercomponent image corresponding to a selected area of the anatomicstructure of the patient determined from the imaging data.
 7. The systemof claim 4 wherein the inner component image includes an aperture image,the aperture image extending from a distal end of the inner componentimage to a proximal end of the inner component image.
 8. The system ofclaim 7 wherein: the distal end of the inner component image is areference end that matches the model of the reamed surface of theanatomic structure of the patient; and wherein the aperture image alignswith an orientation of a guide post according to a final installationposition of a prostheses.
 9. The system of claim 8 wherein: thepatient-specific device generator is configured to generate a guide postimage; the distal end of the inner component image is a reference endthat matches the model of the reamed surface of the anatomic structureof the patient; and the aperture image aligns with an orientation of theguide post image.